Rational Control of Charge Transfer Excitons Toward High‐Contrast Reversible Mechanoresponsive Luminescent Switching

A practicable strategy to rationally obtain the reversible mechanochromic luminescent (MCL) material with high‐contrast ratio (green versus red) has been established. By introducing a volatile third party (small‐sized solvent molecules) into the lattice of charge transfer (CT) cocrystal of mixed‐stacking 1:1 coronene (Cor.) and napthalenetetracarboxylic diimide (NDI), a noteworthy reconfigurable molecular assembly is ingeniously achieved owing to the loosely packing arrangement as well as weakened intermolecular interactions. Accordingly, the CT excited state, strongly corresponding to the molecular stacking modes, can be intentionally tailored through external stimulus (heating, grinding, or solvent), accompanying distinct changes in photophysical properties. Subsequently, a high‐contrast reversible MCL with highly sensitive and good reproducibility is realized and the underlying mechanism is thoroughly revealed. A simple and practicable strategy is established to obtain high‐contrast reversible mechanoresponsive PL switching by introducing a volatile third party into the lattice of mixed‐stacking CT cocrystal. This has the purpose of constructing the loosely packing mode to realize a facile control of molecular assemblies and CT excitons in the solid state.